Whilst still uncommon, this moss is probably under-recorded, as it is so easy to overlook. Its typical habitat is on logs and tree trunks in shaded woodland, so it’s worth taking a look at patches of ‘B. rutabulum’ growing in such places. If the patch is fruiting, you are in luck, as the smooth seta will distinguish this species from its congener. When they are dry, the long-tapering, distinctly pleated leaves, give the branches a more spikey, pointed look than is usual in B. rutabulum. The trouble starts when it is growing on stones and rubble, or around the base of trees, as there are other species that look very similar, in particular B. glareosum and B. mildeanum. Unfortunately, both of these also have smooth setae and long-tapering leaves. To be on the safe side, it’s probably best to take material back to the microscope, as separating these three can be tricky. So here goes…
B. glareosum: dioicous so rarely in fruit, and with a very long drawn-out, often twisted leaf tip on many of the leaves, which are untoothed. Pseudoparaphyllia are sharply triangular. Usually on base-rich ground.
B. mildeanum: autoicous and sometimes in fruit, leaves not really pleated, untoothed and leaf tip not so drawn out and not twisted. The leaf margin is often very straight, as if you had taken a ruler and laid it from the widest part of the leaf straight to the leaf tip. Pseudoparaphyllia are orbicular. Often in very grotty habitats like car parks.
B. salebrosum: autoicous and quite often in fruit. Leaves pleated, slightly toothed, leaf tip again not so drawn out as in B. glareosum and not twisted. The nerve of branch leaves usually ends in a small tooth on the dorsal side. Pseudoparaphyllia are sharply triangular.
As you can see, many of the characters separating these species are a bit woolly…’not so drawn out’, ‘not really pleated’…is it dioicous or have I just failed to find any antheridia? Sometimes decisions have to be made on ‘a balance of characters’, especially when it comes to salebrosum/mildeanum – either that or send your specimen to the referee to sort out. They will love it!Read the Field Guide account